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As illustrated by optical fiber and optical amplification, optical telecommunications have appeared for the last
ten years as one of the most promising candidates to increase the transmission capacities. More recently, the
concept of optical transparency has been investigated and introduced: it consists of the optical routing of
Wavelength Division Multiplexed (WDM) channels without systematic optoelectronic processing at nodes, as
long as propagation impairments remain acceptable [1]. This allows achieving less power-consuming, more
scalable and flexible networks, and today partial optical transparency has become a reality in deployed systems.
However, because of the evolution of traffic features, optical networks are facing new challenges such as
demand for higher transmitted capacity, further upgradeability, and more automation. Making all these
evolutions compliant on the same current network infrastructure with a minimum of upgrades is one of the main
issues for equipment vendors and operators. Hence, an automatic and efficient management of the network needs
a control plan aware of the expected Quality of Transmission (QoT) of the connections to set-up with respect to
numerous parameters such as: the services demanded by the customers in terms of protection/restoration; the
modulation rate and format of the connection under test and also of its adjacent WDM channels; the engineering
rules of the network elements traversed with an accurate knowledge of the associated physical impairments.
Whatever the method and/or the technology used to collect this information, the issue about its accuracy is one
of the main concerns of the network system vendors, because an inaccurate knowledge could yield a sub-optimal
dimensioning and so additional costs when installing the network in the field. Previous studies [1], [2] illustrated
the impact of this knowledge accuracy on the ability to predict the connection feasibility. After describing usual
methods to build performance estimators, this paper reports on this impact but at the global network level,
quantifying the importance to account for these uncertainties from the early network planning step; it also
proposes an improvement of the accuracy of the Quality of Transmission (QoT) estimator to reduce the raise of
planned resources due to these uncertainties.
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